PS. Thanks to Bruno Negrão and Christopher Hicks who referred me to some
list alternatives to ldap@umich.edu. I tried subscribing twice to
ldap@umich.edu and had no success, and it seems that I'm not the only
one experiencing this problem.

The list is known to be dead; I have no idea why Kurt et al continue to
refer people to it,

Not so. I got mail from it today in fact. There may be a problem with
your mail configuration; some lists are pickier than others. Make sure
you are sending and receiving from the same domain/address.